xref: /linux/mm/debug.c (revision ea8a163e02d6925773129e2dd86e419e491b791d) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * mm/debug.c
4  *
5  * mm/ specific debug routines.
6  *
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/mm.h>
11 #include <linux/trace_events.h>
12 #include <linux/memcontrol.h>
13 #include <trace/events/mmflags.h>
14 #include <linux/migrate.h>
15 #include <linux/page_owner.h>
16 #include <linux/ctype.h>
17 
18 #include "internal.h"
19 #include <trace/events/migrate.h>
20 
21 /*
22  * Define EM() and EMe() so that MIGRATE_REASON from trace/events/migrate.h can
23  * be used to populate migrate_reason_names[].
24  */
25 #undef EM
26 #undef EMe
27 #define EM(a, b)	b,
28 #define EMe(a, b)	b
29 
30 const char *migrate_reason_names[MR_TYPES] = {
31 	MIGRATE_REASON
32 };
33 
34 const struct trace_print_flags pageflag_names[] = {
35 	__def_pageflag_names,
36 	{0, NULL}
37 };
38 
39 const struct trace_print_flags gfpflag_names[] = {
40 	__def_gfpflag_names,
41 	{0, NULL}
42 };
43 
44 const struct trace_print_flags vmaflag_names[] = {
45 	__def_vmaflag_names,
46 	{0, NULL}
47 };
48 
49 static void __dump_page(struct page *page)
50 {
51 	struct page *head = compound_head(page);
52 	struct address_space *mapping;
53 	bool compound = PageCompound(page);
54 	/*
55 	 * Accessing the pageblock without the zone lock. It could change to
56 	 * "isolate" again in the meantime, but since we are just dumping the
57 	 * state for debugging, it should be fine to accept a bit of
58 	 * inaccuracy here due to racing.
59 	 */
60 	bool page_cma = is_migrate_cma_page(page);
61 	int mapcount;
62 	char *type = "";
63 
64 	if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
65 		/*
66 		 * Corrupt page, so we cannot call page_mapping. Instead, do a
67 		 * safe subset of the steps that page_mapping() does. Caution:
68 		 * this will be misleading for tail pages, PageSwapCache pages,
69 		 * and potentially other situations. (See the page_mapping()
70 		 * implementation for what's missing here.)
71 		 */
72 		unsigned long tmp = (unsigned long)page->mapping;
73 
74 		if (tmp & PAGE_MAPPING_ANON)
75 			mapping = NULL;
76 		else
77 			mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
78 		head = page;
79 		compound = false;
80 	} else {
81 		mapping = page_mapping(page);
82 	}
83 
84 	/*
85 	 * Avoid VM_BUG_ON() in page_mapcount().
86 	 * page->_mapcount space in struct page is used by sl[aou]b pages to
87 	 * encode own info.
88 	 */
89 	mapcount = PageSlab(head) ? 0 : page_mapcount(page);
90 
91 	pr_warn("page:%p refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
92 			page, page_ref_count(head), mapcount, mapping,
93 			page_to_pgoff(page), page_to_pfn(page));
94 	if (compound) {
95 		if (hpage_pincount_available(page)) {
96 			pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
97 					head, compound_order(head),
98 					head_compound_mapcount(head),
99 					head_compound_pincount(head));
100 		} else {
101 			pr_warn("head:%p order:%u compound_mapcount:%d\n",
102 					head, compound_order(head),
103 					head_compound_mapcount(head));
104 		}
105 	}
106 
107 #ifdef CONFIG_MEMCG
108 	if (head->memcg_data)
109 		pr_warn("memcg:%lx\n", head->memcg_data);
110 #endif
111 	if (PageKsm(page))
112 		type = "ksm ";
113 	else if (PageAnon(page))
114 		type = "anon ";
115 	else if (mapping) {
116 		struct inode *host;
117 		const struct address_space_operations *a_ops;
118 		struct hlist_node *dentry_first;
119 		struct dentry *dentry_ptr;
120 		struct dentry dentry;
121 		unsigned long ino;
122 
123 		/*
124 		 * mapping can be invalid pointer and we don't want to crash
125 		 * accessing it, so probe everything depending on it carefully
126 		 */
127 		if (get_kernel_nofault(host, &mapping->host) ||
128 		    get_kernel_nofault(a_ops, &mapping->a_ops)) {
129 			pr_warn("failed to read mapping contents, not a valid kernel address?\n");
130 			goto out_mapping;
131 		}
132 
133 		if (!host) {
134 			pr_warn("aops:%ps\n", a_ops);
135 			goto out_mapping;
136 		}
137 
138 		if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
139 		    get_kernel_nofault(ino, &host->i_ino)) {
140 			pr_warn("aops:%ps with invalid host inode %px\n",
141 					a_ops, host);
142 			goto out_mapping;
143 		}
144 
145 		if (!dentry_first) {
146 			pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
147 			goto out_mapping;
148 		}
149 
150 		dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
151 		if (get_kernel_nofault(dentry, dentry_ptr)) {
152 			pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
153 					a_ops, ino, dentry_ptr);
154 		} else {
155 			/*
156 			 * if dentry is corrupted, the %pd handler may still
157 			 * crash, but it's unlikely that we reach here with a
158 			 * corrupted struct page
159 			 */
160 			pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
161 					a_ops, ino, &dentry);
162 		}
163 	}
164 out_mapping:
165 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
166 
167 	pr_warn("%sflags: %pGp%s\n", type, &head->flags,
168 		page_cma ? " CMA" : "");
169 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
170 			sizeof(unsigned long), page,
171 			sizeof(struct page), false);
172 	if (head != page)
173 		print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
174 			sizeof(unsigned long), head,
175 			sizeof(struct page), false);
176 }
177 
178 void dump_page(struct page *page, const char *reason)
179 {
180 	if (PagePoisoned(page))
181 		pr_warn("page:%p is uninitialized and poisoned", page);
182 	else
183 		__dump_page(page);
184 	if (reason)
185 		pr_warn("page dumped because: %s\n", reason);
186 	dump_page_owner(page);
187 }
188 EXPORT_SYMBOL(dump_page);
189 
190 #ifdef CONFIG_DEBUG_VM
191 
192 void dump_vma(const struct vm_area_struct *vma)
193 {
194 	pr_emerg("vma %px start %px end %px\n"
195 		"next %px prev %px mm %px\n"
196 		"prot %lx anon_vma %px vm_ops %px\n"
197 		"pgoff %lx file %px private_data %px\n"
198 		"flags: %#lx(%pGv)\n",
199 		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
200 		vma->vm_prev, vma->vm_mm,
201 		(unsigned long)pgprot_val(vma->vm_page_prot),
202 		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
203 		vma->vm_file, vma->vm_private_data,
204 		vma->vm_flags, &vma->vm_flags);
205 }
206 EXPORT_SYMBOL(dump_vma);
207 
208 void dump_mm(const struct mm_struct *mm)
209 {
210 	pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
211 #ifdef CONFIG_MMU
212 		"get_unmapped_area %px\n"
213 #endif
214 		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
215 		"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
216 		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
217 		"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
218 		"start_code %lx end_code %lx start_data %lx end_data %lx\n"
219 		"start_brk %lx brk %lx start_stack %lx\n"
220 		"arg_start %lx arg_end %lx env_start %lx env_end %lx\n"
221 		"binfmt %px flags %lx\n"
222 #ifdef CONFIG_AIO
223 		"ioctx_table %px\n"
224 #endif
225 #ifdef CONFIG_MEMCG
226 		"owner %px "
227 #endif
228 		"exe_file %px\n"
229 #ifdef CONFIG_MMU_NOTIFIER
230 		"notifier_subscriptions %px\n"
231 #endif
232 #ifdef CONFIG_NUMA_BALANCING
233 		"numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n"
234 #endif
235 		"tlb_flush_pending %d\n"
236 		"def_flags: %#lx(%pGv)\n",
237 
238 		mm, mm->mmap, (long long) mm->vmacache_seqnum, mm->task_size,
239 #ifdef CONFIG_MMU
240 		mm->get_unmapped_area,
241 #endif
242 		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
243 		mm->pgd, atomic_read(&mm->mm_users),
244 		atomic_read(&mm->mm_count),
245 		mm_pgtables_bytes(mm),
246 		mm->map_count,
247 		mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
248 		(u64)atomic64_read(&mm->pinned_vm),
249 		mm->data_vm, mm->exec_vm, mm->stack_vm,
250 		mm->start_code, mm->end_code, mm->start_data, mm->end_data,
251 		mm->start_brk, mm->brk, mm->start_stack,
252 		mm->arg_start, mm->arg_end, mm->env_start, mm->env_end,
253 		mm->binfmt, mm->flags,
254 #ifdef CONFIG_AIO
255 		mm->ioctx_table,
256 #endif
257 #ifdef CONFIG_MEMCG
258 		mm->owner,
259 #endif
260 		mm->exe_file,
261 #ifdef CONFIG_MMU_NOTIFIER
262 		mm->notifier_subscriptions,
263 #endif
264 #ifdef CONFIG_NUMA_BALANCING
265 		mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
266 #endif
267 		atomic_read(&mm->tlb_flush_pending),
268 		mm->def_flags, &mm->def_flags
269 	);
270 }
271 
272 static bool page_init_poisoning __read_mostly = true;
273 
274 static int __init setup_vm_debug(char *str)
275 {
276 	bool __page_init_poisoning = true;
277 
278 	/*
279 	 * Calling vm_debug with no arguments is equivalent to requesting
280 	 * to enable all debugging options we can control.
281 	 */
282 	if (*str++ != '=' || !*str)
283 		goto out;
284 
285 	__page_init_poisoning = false;
286 	if (*str == '-')
287 		goto out;
288 
289 	while (*str) {
290 		switch (tolower(*str)) {
291 		case'p':
292 			__page_init_poisoning = true;
293 			break;
294 		default:
295 			pr_err("vm_debug option '%c' unknown. skipped\n",
296 			       *str);
297 		}
298 
299 		str++;
300 	}
301 out:
302 	if (page_init_poisoning && !__page_init_poisoning)
303 		pr_warn("Page struct poisoning disabled by kernel command line option 'vm_debug'\n");
304 
305 	page_init_poisoning = __page_init_poisoning;
306 
307 	return 1;
308 }
309 __setup("vm_debug", setup_vm_debug);
310 
311 void page_init_poison(struct page *page, size_t size)
312 {
313 	if (page_init_poisoning)
314 		memset(page, PAGE_POISON_PATTERN, size);
315 }
316 EXPORT_SYMBOL_GPL(page_init_poison);
317 #endif		/* CONFIG_DEBUG_VM */
318